MediaWiki 1.30.2

[autoinstallsdev/mediawiki.git] / includes / libs / RiffExtractor.php

diff --git a/includes/libs/RiffExtractor.php b/includes/libs/RiffExtractor.php
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+<?php
+/**
+ * Extractor for the Resource Interchange File Format
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ * http://www.gnu.org/copyleft/gpl.html
+ *
+ * @file
+ * @author Bryan Tong Minh
+ * @ingroup Media
+ */
+
+class RiffExtractor {
+       public static function findChunksFromFile( $filename, $maxChunks = -1 ) {
+               $file = fopen( $filename, 'rb' );
+               $info = self::findChunks( $file, $maxChunks );
+               fclose( $file );
+               return $info;
+       }
+
+       public static function findChunks( $file, $maxChunks = -1 ) {
+               $riff = fread( $file, 4 );
+               if ( $riff !== 'RIFF' ) {
+                       return false;
+               }
+
+               // Next four bytes are fileSize
+               $fileSize = fread( $file, 4 );
+               if ( !$fileSize || strlen( $fileSize ) != 4 ) {
+                       return false;
+               }
+
+               // Next four bytes are the FourCC
+               $fourCC = fread( $file, 4 );
+               if ( !$fourCC || strlen( $fourCC ) != 4 ) {
+                       return false;
+               }
+
+               // Create basic info structure
+               $info = [
+                       'fileSize' => self::extractUInt32( $fileSize ),
+                       'fourCC' => $fourCC,
+                       'chunks' => [],
+               ];
+               $numberOfChunks = 0;
+
+               // Find out the chunks
+               while ( !feof( $file ) && !( $numberOfChunks >= $maxChunks && $maxChunks >= 0 ) ) {
+                       $chunkStart = ftell( $file );
+
+                       $chunkFourCC = fread( $file, 4 );
+                       if ( !$chunkFourCC || strlen( $chunkFourCC ) != 4 ) {
+                               return $info;
+                       }
+
+                       $chunkSize = fread( $file, 4 );
+                       if ( !$chunkSize || strlen( $chunkSize ) != 4 ) {
+                               return $info;
+                       }
+                       $intChunkSize = self::extractUInt32( $chunkSize );
+
+                       // Add chunk info to the info structure
+                       $info['chunks'][] = [
+                               'fourCC' => $chunkFourCC,
+                               'start' => $chunkStart,
+                               'size' => $intChunkSize
+                       ];
+
+                       // Uneven chunks have padding bytes
+                       $padding = $intChunkSize % 2;
+                       // Seek to the next chunk
+                       fseek( $file, $intChunkSize + $padding, SEEK_CUR );
+
+               }
+
+               return $info;
+       }
+
+       /**
+        * Extract a little-endian uint32 from a 4 byte string
+        * @param string $string 4-byte string
+        * @return int
+        */
+       public static function extractUInt32( $string ) {
+               return unpack( 'V', $string )[1];
+       }
+};